Vehicle HVAC system

ABSTRACT

An auxiliary climate control system may include a plurality of evaporators arranged in series. The auxiliary climate control system may comprise a first evaporator coupled to a first compressor and a first condenser, a second evaporator coupled to a second compressor and a second condenser, and a blower configured to move air past the first evaporator and the second evaporator. The first compressor may be configured to operate when a vehicle engine is running and the second compressor is configured to operate on power from a source independent of the running engine such that the second compressor may operate when the engine is not running.

The present application claims benefit of priority to U.S. ProvisionalApplication Ser. No. 60/827,620, filed Sep. 29, 2006, the entirecontents of which is incorporated herein by reference.

This application relates generally to climate control (heating,ventilating and air-conditioning, or HVAC) systems. More particularly,this application relates to HVAC systems used for motor vehicles.

BACKGROUND

Primary HVAC systems are often included for climate control of motorvehicles. These systems heat and/or cool air circulated in the occupantcabin of the vehicle. Some of these systems require energy from thevehicle engine such that the vehicle engine must be running (i.e.idling) for the HVAC system to be fully functional when the vehicle isparked. This is particularly an issue with vehicles that are commonlyoccupied while parked, such as recreational vehicles (RVs), busses,commercial trucks with sleeper cabs, and other such vehicles. However,idling a vehicle engine for a period of time to operate the HVAC systemconsumes relatively large quantities of fuel and generates exhaust.

To avoid unnecessary fuel consumption and limit the generation ofexhaust while still providing a comfortable cabin temperature, auxiliaryHVAC units that are independent of the vehicle engine have been used.These systems are generally free standing from the primary HVAC systemof the vehicle. Such systems may require distribution ducting that isindependent of the primary HVAC system. These systems may also requireseparate control interfaces from those for the primary HVAC system.These systems may also require multiple blower motors for use with theprimary and auxiliary HVAC systems.

Accordingly, there is a need for an integrated auxiliary HVAC systemthat incorporates the primary and auxiliary HVAC systems. There is alsoa need for an integrated HVAC system that may be controlled by a singleuser interface.

SUMMARY

One embodiment relates to an auxiliary climate control system includinga plurality of evaporators arranged in series. In some of theseembodiments, an auxiliary climate control system for a vehicle comprisesa first evaporator coupled to a first compressor and a first condenser,a second evaporator coupled to a second compressor and a secondcondenser, and a blower configured to move air past the first evaporatorand the second evaporator. The first compressor may be configured tooperate when a vehicle engine is running and the second compressor isconfigured to operate on power from a source independent of the runningengine such that the second compressor may operate when the engine isnot running.

Other embodiments relate to an auxiliary climate control system for avehicle comprising a first evaporator in fluid communication with afirst compressor and a first condenser; a second evaporator in fluidcommunication with a second compressor and a second condenser; and ablower configured to move air past both the first evaporator and thesecond evaporator. In these embodiments, the first evaporator is not influid communication with the second evaporator.

In yet other embodiments, an auxiliary climate control system for avehicle may comprise a first evaporator in fluid communication with afirst compressor and a first condenser; a second evaporator in fluidcommunication with a second compressor and a second condenser; a blowerconfigured to move air past both the first evaporator and the secondevaporator; and a heater core in fluid communication with a coolantheater. In these embodiments, an actuator may be configured to directsome portion or all of the air flow past the heater core.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an integrated HVAC system.

FIG. 2 is a fragmentary cross-sectional view of a portion the HVACsystem of FIG. 1.

FIG. 3 is a fragmentary cross-sectional view of a portion the HVACsystem of FIG. 1.

FIG. 4, is a side elevation view of a portion of the HVAC system of FIG.1.

FIG. 5 is a front elevation view of a portion of the HVAC system of FIG.1.

FIG. 6 is a schematic view of a coolant loop.

FIG. 7 is a schematic view of a vehicle HVAC system.

DETAILED DESCRIPTION

FIG. 1 illustrates an integrated HVAC system for use in a vehicle. Theintegrated HVAC unit includes an auxiliary HVAC unit and acompressor/condenser unit. The auxiliary HVAC unit may be containedwithin the cab and generally includes an air inlet, a blower with alinear power module, such as, for example, a brushless direct current(BLDC) blower motor, a starter module 5 a and air outlets 9.

In the preferred embodiment of FIG. 1, the compressor/condenser unit 1is configured to be mounted on the exterior of the vehicle. Condensedrefrigerant is circulated from the condenser to the 2^(nd) evaporator 2of the auxiliary HVAC unit (shown in FIG. 2). Condensed refrigerant isevaporated to cool air entering the air inlet 3 of the auxiliary HVACunit. The evaporated refrigerant is then recirculated to thecompressor/condenser unit 1 as in a conventional refrigeration cycle.

In this preferred embodiment, a coolant heater 4 is coupled to thecompressor/condenser unit 1. In a preferred exemplary embodiment, thecoolant heater 4 may be a fuel fired heater (FFH) that bums fuel fromthe vehicle fuel supply to heat the cabin. One suitable FFH is a dieselfueled heater commercially available from ESPAR of Mississauga, Ontario.In the case of a FFH, the coolant heater may be coupled to thecompressor/condenser unit 1 on the exterior of the vehicle to allow forsafe venting of exhaust gasses. Alternatively, the coolant heater 4 maybe mounted closer to or on the auxiliary HVAC unit if, for example, thecoolant heater 4 is an electric heater or other device that does notrequire venting of exhaust gasses.

In some embodiments, the coolant heater 4 may be coupled to the enginecooling system such that engine coolant may be circulated through thecoolant heater and the heater core in the auxiliary HVAC unit.Alternatively, the coolant heater 4 and heater core may be isolated fromthe engine cooling system (i.e. on a separate closed coolant loop).

The integrated HVAC systems may be powered by a variety of power sourcesthat are independent of the engine. For example, the auxiliary HVACsystem may be powered by an auxiliary power unit (APU), vehiclebatteries, batteries dedicated to the auxiliary HVAC system, or shorepower (i.e. AC power). In one preferred embodiment, the compressor motoris designed as a 110 volt AC motor.

FIGS. 2 and 3 illustrate the auxiliary HVAC unit of FIG. 1 and thegeneral flow of air therethrough. The auxiliary HVAC unit generallyincludes an air inlet 3, a 2^(nd) evaporator 2, a blower motor 5 suchas, for example, a BLDC blower motor, a main evaporator 6, an actuator(shown as a temperature door (temp. door)) 7, a heater core 8, and anair outlet 9. An air inlet filter 10 may be positioned in the air inlet3 to remove particulates that may damage the auxiliary HVAC unit or thatare not desired in the outlet air stream. An air inlet sensor 11 mayalso be used to monitor the temperature of the air entering the unit anda freeze protection sensor 12 may be used to detect ice forming on ornear the 2^(nd) evaporator 2.

As illustrated in FIG. 3, in some embodiments, air may be drawn into theair inlet by the blower motor. The inlet air may be recirculated fromthe cabin, or the air may be fresh air drawn from outside the vehicle.The temperature of the inlet air is measured by the air inlet sensor.This temperature measurement may be used by a controller logic thatcontrols the coolant heater, refrigerant system, temperature door,and/or blower motor. The air passes through the 2^(nd) evaporator wherethe air may be cooled. The 2^(nd) evaporator is coupled to thecompressor/condenser unit (shown in FIG. 1) which is operated when thevehicle is parked and not idling.

The air is then drawn into the blower motor where it is accelerated.Upon exiting the blower motor, the air stream passes through the mainevaporator where it may be cooled. The main evaporator may be coupled tothe vehicles primary air cooling system (i.e. the primary compressor andcondenser). The air then passes the temperature door.

The temperature door may be controlled to regulate the flow of airthrough the heating core. When the temperature door is moved to aposition for maximum cooling, the temperature door blocks airflow to theheating core such that the cool air that has been cooled at one or moreof the evaporators bypasses the heating core. When the system is usedfor maximum heating, the temperature door directs substantially all ofthe air flow through the passage where the heating core is located. Heatis supplied to the heater core by hot circulated coolant (e.g., anethylene glycol and water mixture) that has been heated in the coolantheater (e.g. the FFH coupled to the compressor/condenser unit).

The heated or cooled air then passes a discharge sensor 13 that measuresthe temperature of the air exiting the auxiliary HVAC unit. Thetemperature measurement may be used by a controller logic that controlsthe coolant heater, refrigerant system, temperature door, and/or blowermotor.

The air then exits the auxiliary HVAC unit at the air outlet. The airoutlet may be coupled to an auxiliary duct system, or the vehiclesprimary air distribution system.

When the vehicle engine is running, the 2^(nd) evaporator may be used inconjunction with the main evaporator to cool the cabin air (i.e. toprovide additional cooling capacity when required). In alternativeembodiments, the 2^(nd) evaporator and the main evaporator may both beupstream of the blower motor (i.e. between the inlet and the blowermotor). In yet other embodiments, both the 2^(nd) evaporator and themain evaporator may both be down steam of the blower motor. In even yetother embodiments, the 2^(nd) evaporator may be downstream of the blowermotor while the main evaporator is upstream of the evaporator.

The auxiliary HVAC unit may be positioned in a cabin zone. For example,in a commercial truck, the auxiliary unit may be placed in a sleepercab. In such embodiments, the main evaporator may be coupled to thevehicle's primary HVAC system to cool the sleeper cab while the vehicleis operating. If needed, the auxiliary HVAC unit may be used to provideadditional cooling capacity. When the vehicle is parked and not idling(i.e. for a driver break) the main evaporator is not used but the 2^(nd)evaporator is used to cool the sleeper cab. The externalcompressor/condenser unit is used to supply condensed refrigerant to thecondenser and may be powered by an APU, vehicle batteries, batteriesdedicated to the auxiliary HVAC system, and/or shore power such as a 110volt AC power supply.

FIGS. 4 and 5 illustrate the compressor/condenser unit shown in FIG. 1.Expanded refrigerant is circulated to the compressor where therefrigerant is pressurized. The compressed refrigerant is liquefied inthe condenser. The pressurized liquid refrigerant passes through coolantlines 14 and is then evaporated in the 2^(nd) evaporator to absorb heatfrom the inlet air. Because the compressor, condenser, and evaporatorcomprise a closed loop, these components may be pre-charged withrefrigerant prior to installation in a vehicle.

The auxiliary HVAC unit may include a control interface for a user toselect the temperature and/or blower speed. In some embodiments, thesame controller interface may be used to regulate both the mainevaporator when the vehicle is operating and the 2^(nd) evaporator whenthe vehicle is parked and not idling. In a preferred embodiment, thevehicle operator is provide with a single control panel to control thecabin comfort irrespective of whether either or both of the first andsecond refrigeration systems (i.e., main and 2^(nd) evaporators) is/areoperating. For example, the single control panel may have only twocontrol settings, one for temperature and another for fan speed.

The heater core of the auxiliary HVAC unit receives circulated, heatedcoolant from the coolant heater via a coolant line 15. In someembodiments the coolant heater is a FFH. The FFH may be operated usingthe vehicles fuel (i.e. gasoline or diesel). An exhaust port 16 ventsthe FFH exhaust to the exterior of the cabin.

FIG. 6 illustrates a coolant loop layout that may be employed with theauxiliary HVAC system. In some embodiments, a main HVAC heater corereceives hot coolant from the vehicle engine when the vehicle isrunning. The engine coolant is also circulated to the coolant heater(shown as a fuel fired heater) which is in series with the heater coreof the auxiliary HVAC unit. The heater core and coolant heater are inparallel with the main HVAC heater core. When the vehicle is parked andnot idling, coolant may be heated in the coolant heater and circulatedto the heater core to warm the air in a cabin zone (e.g. the sleepercab). The coolant is also circulated to the main HVAC heater core suchthat other areas of the cabin may be heated. Valve B is closed toprevent circulation of the coolant to the engine where heat would belost.

When the engine is running, valve B and valve A may be opened to utilizeheat generated by the engine for heating the cabin. Valve A may also beclosed such that hot coolant is circulated to the engine to warm theengine up prior to or just after starting.

FIG. 7 illustrates a schematic view of a vehicle HVAC system. The HVACsystem includes three separate loops: cooling loop A, cooling loop B,and heating loop C. Cooling loop A comprises an auxiliary compressor 20,an auxiliary condenser 21 and a 2^(nd) evaporator 22. In someembodiments, the auxiliary compressor 20 is powered by a power sourceindependent of the running vehicle engine. Included in such powersources are the vehicle batteries or other batteries that may berecharged when the engine is running. Alternatively, the auxiliarycompressor may run on shore power.

Cooling loop B comprises a main compressor 23, a main condenser 24, amain evaporator 25 and a 2^(nd) main evaporator 26. The main evaporator25 and 2^(nd) main evaporator 26 are shown in parallel, however, themain evaporator 25 and second main evaporator 26 could be arranged inseries. Alternatively, the main evaporator 25 and 2^(nd) main evaporator26 could be on separate cooling loops. The main evaporator 25 and secondmain evaporator 26 may be used to cool zones of a vehicle cabin. Forexample, the main evaporator 25 may be located in the sleeper cab of acommercial truck, while the 2^(nd) main evaporator 26 may be locatednear the driver's area of the cab to allow cooling of multiple zonesfrom cooling loop B. The main compressor may, in some embodiments, bepowered by mechanical energy generated by the vehicles engine.

Heating loop C is configured as the loop shown in FIG. 6. Heating loop Ccomprises a coolant heater (shown as a fuel fired heater) 27, a heatercore 28, a main heater core 29, and the vehicle engine 30. Valves A31and B32 regulate the flow of coolant as described above.

The auxiliary condenser 21, auxiliary compressor 20, and coolant heater27 may be located in the compressor/condenser unit 32 mounted on theexterior of the vehicle (see FIG. 1). The main evaporator 25, 2^(nd)evaporator 26, and the heater core may be located in the auxiliary HVACunit, as shown in FIG. 2. Alternatively, the auxiliary condenser 21,auxiliary compressor 20, and coolant heater 27 may be integrated intothe auxiliary HVAC unit 33, to produce a single compact unit that isdesigned to be mounted inside of the vehicle cab, preferably adjacent anoutside wall. In such an embodiment, a single casing would encompassboth of the portions that are shown in FIG. 7 as being encompassed byseparate casings.

Placing the 2^(nd) evaporator 22 and the main evaporator 25 in theauxiliary HVAC unit 33, preferably in the same air flow pathway,facilitates the use of a single control interface for operation of theauxiliary HVAC unit 33 to both cool a cabin zone when the vehicle isrunning and when the vehicle is parked and not idling. The controlinterface may be mounted to the auxiliary HVAC unit 33 and may comprisetwo controls such as dials or switches. The two controls may be used toregulate temperature and fan speed. This single control interfacetherefore operates both the main HVAC system and the auxiliary HVACsystem 33, improving both the convenience and the compactness/costeffectiveness of the system according to the invention. The latteradvantages are further enhanced due to the fact that the main HVAC andauxiliary HVAC systems also share a single fan and ducting structure inthe auxiliary unit.

Although the foregoing has been described with reference to examplaryembodiments, workers skilled in the art will recognize that changes maybe made in form and detail without departing from the spirit and scopethereof. For example, although different example embodiments may havebeen described as including one or more features providing one or morebenefits, it is contemplated that the described features may beinterchanged with one another or alternatively be combined with oneanother in the described example embodiments or in other alternativeembodiments. The present subject matter described with reference to theexample embodiments and set forth in the following claims is manifestlyintended to be as broad as possible. For example, unless specificallyotherwise noted, the claims reciting a single particular element alsoencompass a plurality of such particular elements.

1. An auxiliary climate control system for a vehicle comprising: a firstevaporator coupled to a first compressor and a first condenser; a secondevaporator coupled to a second compressor and a second condenser; ablower configured to move air past the first evaporator and the secondevaporator; wherein the first compressor is configured to operate when avehicle engine is running; and the second compressor is configured tooperate on power from a source such that the second compressor mayoperate when the engine is not running.
 2. The auxiliary climate controlsystem of claim 1, wherein the second compressor is configured tooperate on power supplied by shore power.
 3. The auxiliary climatecontrol system of claim 1, wherein the one of the first evaporator andthe second evaporator is upstream of the blower and the other of thefirst evaporator and the second evaporator is downstream of the blower.4. The auxiliary climate control system of claim 1, further comprising aheater core coupled to a coolant heater.
 5. The auxiliary climatecontrol system of claim 4, wherein the coolant heater is coupled to theengine coolant system.
 6. An auxiliary climate control system for avehicle comprising: a first evaporator in fluid communication with afirst compressor and a first condenser; a second evaporator in fluidcommunication with a second compressor and a second condenser; a blowerconfigured to move air past both the first evaporator and the secondevaporator; and wherein the first evaporator is not in fluidcommunication with the second evaporator.
 7. An auxiliary climatecontrol system for a vehicle comprising: a first evaporator in fluidcommunication with a first compressor and a first condenser; a secondevaporator in fluid communication with a second compressor and a secondcondenser; a blower configured to move air past both the firstevaporator and the second evaporator; a heater core in fluidcommunication with a coolant heater; an actuator configured to directair flow past one or more of the first evaporator, the secondevaporator, and the heater core.
 8. A method for controlling thetemperature of a vehicle cabin comprising: passing inlet air past afirst evaporator, the first evaporator coupled to a first compressor;passing the inlet air past a second evaporator, the second evaporatorcoupled to a second compressor; wherein the first compressor isconfigured to operate when a vehicle engine is running; and the secondcompressor is configured to operate on power from a source independentsuch that the second compressor may operate when the engine is notrunning.
 9. A method for controlling the temperature of a vehicle cabincomprising: passing air through an HVAC unit comprising a firstevaporator and a second evaporator; controlling the temperature of theair exiting the HVAC unit both when the vehicle engine is running andwhen the engine is off using a single controller interface; wherein thefirst evaporator is coupled to a first compressor configured to operatewhen a vehicle engine is running; and the second evaporator is coupledto a second compressor configured to operate on power from a source suchthat the second compressor may operate when the engine is not running.